MCP Tool

An MCP tool is a callable function exposed by an MCP server that a language model can invoke to perform actions with side effects — such as running a query, sending an email, or writing a file. Each tool is described by a name, a human-readable description, and a JSON Schema that defines its input parameters. The model selects tools by name based on the descriptions surfaced during tool discovery, and the server executes the function and returns a structured result.